A Better Mousetrap is the ninth episode of the Beast Wars TV series.
In the caverns beneath the Axalon, Blackarachnia, Waspinator, and Terrorsaur dig a hole to deliver a sonic emitter that will allow the Predacons to access the Maximal base unhindered. When Waspinator leaves, Terrorsaur is stuck doing the labor.
On board the Axalon, Rhinox shows a holographic simulation of the Axalon's new defenses to Rattrap and Optimus Primal. Cheetor detects a Predacon in a sector of Maximal territory. Primal and Tigatron go to see why Waspinator has been buzzing around the area a lot recently.
Dinobot is unimpressed by how non-lethal the Axalon's new defenses are. Rattrap activates the defense against Dinobot to display how effective they can be. The enraged Dinobot breaks free from the restraints fastened around him and attacks the rat—but misses and impales the controls for the entire base's defense grid. The console registers the Maximals as intruders, forcing the occupants of the base to vacate. Rattrap stays behind and hides inside of a ventilation shaft so he can figure out how to disable the defenses.
Tigatron and Optimus Primal find Waspinator high on sugar and flying around aimlessly. When Primal gets Waspinator's attention, he runs away. Primal chases after, and has a surprisingly hard time keeping up with the hyperactive hornet. Primal returns home to see what irregularities are going on with Sentinel. Hunting alone, Tigatron follows Waspinator's scent through a tunnel—the entrance hidden by a holographic projector.
Inside the Axalon, Rattrap works his away around a pool of zero friction fluid by surfing over it. He scampers and dances to avoid other defensive systems. His marksman and demolitions expert skills come in useful as he works his way towards the ship's core.
Optimus Primal arrives at the Axalon and meets with the others locked outside. They explain what the situation is and where Rattrap is.
Tigatron finds the three Predacons underground in their excavation operation. He grabs their device and runs away with it. Blackarachnia demands he return it, explaining that the device is an explosive. Tigatron complies and tosses it at the Predacons, who all run away from the machine before it detonates. Tigatron also races away, and when the device explodes, it collapses a huge portion of the land outside of the Axalon, but not harming the Axalon itself. One battle over, Tigatron meets with the rest of the Maximals.
Rattrap enters the room where Sentinel's core is stored. The internal defenses continue to try to purge him. But before he's terminated, he hits the big red button to deactivate Sentinel.
Outside, the shield deactivates. Rhinox determines that this is because Rattrap must have been killed by the haywire defenses. The Maximals sadly say a few words to remember their annoying stinky friend who sacrificed himself trying to save them.
...until the Axalon hatch opens, and out comes Rattrap, alive and well, his mission a success.